ABSTRACT
The self-sustained oscillation o f the cavity shear layer differs drastically from a free unforced shear layer. The self-sustained oscillation within the cavity is caused primarily by the feedback o f strong phase coherence, which the unforced shear layer does not have. Thus, the self-sustained oscillation within the cavity exhibits a sharp spectrum at a particular fre quency while the free shear layer yields only a broadband spectrum around the “most unstable” frequency. As a result, perpetually large pressure fluctuation will cause fatigue damages to the com ponents inside the cavity. Moreover, acute noise and significant increase o f cavity drag (Gharib and Roshko 1987) are also the results o f self-sustaining oscillation within the cavity. To minimize these un desirable results, insightful understanding o f the os cillatory characteristics within cavity is worth fur ther investigations.
